This research project is investigating some cortical correlates of attention during natural speech perception. Specifically, we are attempting to test the hypothesis that speech perception involves phasic, rather than continuous attention, and is characterized by bursts of cognitive activity at specificable linguistic boundaries in the stream of speech. The method involves the measurement of the average evoked response to irrelevant stimuli--light flashes--while the subject is attending to a tape-recorded dialogue. If the hypothesis is correct, the evoked response should be relatively inhibited when the stimulus is timed to occur during the postulated bursts of cognitive activity at linguistic boundaries. During the period covered by this report two studies of this phenomenon were carried out. Both were inconclusive because of unforeseen methodological problems. A third study is underway, incorporating the necessary design refinements. If future studies support the fundamental hypothesis this method will be used to investigate attentional deficits in schizophrenia with particular regard for the lateral specification of cortical function. This study has considerable potential leverage for the problem for hemispheric laterality and attention, since the left hemisphere seems clearly to be specialized for speech processing.